I 정수장의 UV 공정 적용을 통한 소독능 제고 및 관망 잔류염소 적정 운영 효과 예측

박종일(Jong-Il Park),이영(Young Lee),김건회(Keon-Hoi Kim),이태훈(Tae-Hoon Lee),박철종(Cheol-Jong Park),유정희(Jeong-Hee Yoo) 대한환경공학회 2019 대한환경공학회지 Vol.41 No.11

목적 : 본 연구에서는 I정수장에 고도공정으로 도입된 UV 공정을 활용한 소독능 제고 및 관망 잔류염소 적정 운영효과를 분석하였다. 방법 : Virus 및 Giardia 불활성화비 계산은 환경부에서 개발한 “소독능 계산 프로그램”을 활용하였으며, 수질인자(잔류염소, 수온 등)는 자동측정기로 측정 및 저장하였다. 동절기 최악 수질 조건 시 용수생산량별 Giardia 불활성화비 1.1 이상 만족을 위한 정수지 잔류염소 농도를 산정하고, EPANET2.0을 통해 해당 조건에서의 공급과정 잔류염소 농도를 모의하였다. I정수장 UV 설비의 UV 조사량 인증 시험은 UVDGM 2006에 의거하여 HDR|HydroQual에서 수행하였다. UV 소독 적용시의 Giardia 불활성화비를 도출한 후, 공급과정 잔류염소 적정 운영을 위한 정수지 잔류염소 농도를 산정하였다. 염소 단독 소독과 UV 병행 소독 시의 약품비 및 전력비를 통해 원단위를 산출하여 경제성을 비교하였다. 결과 및 토의 : I정수장에서 염소 단독 소독으로 동절기시 Giardia 불활성화비 1.1 이상 달성을 위해서는 정수지 잔류염소 농도를 0.73-1.59 mg/L로 운영하여야 하는 것으로 산정되었다. 이 경우 관말 배수지 잔류염소 농도는 0.63-1.42 mg/L로 나타났다. I정수장의 UV 설비를 소독에 적용할 경우, 반응조당 1개 섹션을 가동전력 100%로 운영 시 인증조사량(VD)은 21.3 mJ/cm²로 도출되었다. 이는 Giardia 불활성화비 1.936, Cryptosporidium 불활성화비 1.775에 해당하는 값이었다. 이를 통하여 UV 소독으로 Giardia 및 Cryptosporidium의 안정적인 소독이 가능할 것으로 사료되었다. 또한 UV 소독 적용 시 정수지 잔류염소는 0.59-0.65 mg/L (관말 배수지 잔류염소 농도 0.5 mg/L 유지 수준)로 운영할 수 있다고 산정되었다. 경제성 분석 결과, 용수생산량 190,000-250,000 m³/일인 경우 UV 소독을 병행하면 NaOCl 단독 소독 대비 원단위를 0.02-0.85 원/m³ 절감할 수 있을 것으로 예상되었다. 결론 : I정수장 UV 공정 적용 시 높은 소독 효율 확보와 정수지 및 관망 잔류염소 농도의 적정 운영이 가능할 것으로 판단되었다. 이를 통하여 약품비의 절감은 물론 소독부산물 발생 농도 저감이 예상되었다. 또한, UV의 Giardia 및 Cryptosporidium에 대한 소독효과가 높아 기존의 염소소독을 효과적으로 보완할 수 있을 것으로 기대되었다. Objectives : In this study, disinfection efficiency improvement and optimal operation of residual chlorine were analyzed when apply UV (Ultraviolet) process in I WTP (Water Treatment Plant). Methods : Inactivation ratios of virus and Giardia were calculated by “Disinfection efficiency calculation program” which was made by Ministry of Environment. Water quality factors (residual chlorine, temperature, etc) were measured and saved by auto measuring instruments. Residual chlorine in clean water reservoir was calculated for satisfy the inactivation ratio of Giardia over 1.1 at worst case of water quality condition in winter season. Residual chlorine in distribution reservoir was simulated by EPANET2.0. UV dose validation test of UV facilities in I WTP was conducted by HDR|HydroQual according to UVDGM (Ultraviolet Disinfection Guidance Manual) 2006 of US EPA (United States Environmental Protection Agency). Inactivation ratio of Giardia by application of UV disinfection and optimal concentration of residual chlorine in clean water reservoir for optimal operation of water distribution line were calculated. Economical efficiency was compared by price unit of chlorine sole disinfection and UV combined disinfection. Results and Discussion : In order to satisfy the inactivation ratio of Giardia over 1.1 by chlorine sole disinfection, residual chlorine in clean water reservoir should be operated within 0.73-1.59 mg/L. In this case, residual chlorine of distribution reservoir at the end of water distribution line was 0.63-1.42 mg/L. If UV process of I WTP was applied to disinfection, validation dose (VD) would be estimated 21.3 mJ/cm² when operating 1 section per reactor at 100% ballistic power level. Which value corresponded to inactivation ratio of Giardia 1.936 and Cryptosporidium 1.775. Through this, it would be possible to secure effective disinfection of Giardia and Cryptosporidium, and reduce post chlorine injection. In application of UV disinfection, residual chlorine in clean water reservoir could be operated within 0.59-0.65 mg/L (residual chlorine in distribution reservoir at the end of distribution line would be 0.5 mg/L level). By the result of economical efficiency analysis, when water production is 190,000-250,000 m³/d, UV combined disinfection would be saved the price unit within 0.02-0.85 KRW/m³ comparing with chlorine (NaOCl) sole disinfection. Conclusions : If UV process in I WTP was applied to disinfection, it would be possible to secure high disinfection efficiency and optimal operation of residual chlorine in clean water reservoir and distribution line. Through this, it would be expected to economize chemical costs and decrease the concentration of disinfection byproducts. In addition, UV has high disinfection effect against Giardia and Cryptosporidium, it would be expected to effectively complement the chlorine sole disinfection.

2-MIB 처리 및 잔류오존 제거를 위한 G정수장 Peroxone(O₃/H₂O₂-AOP)-Quenching 공정 최적화 연구

박종일(Jong-Il Park),이영(Young Lee),장경아(Kyoung-A Jang),김태훈(Tae-Hoon Kim),박철종(Cheol-Jong Park),유정희(Jeong-Hee Yoo) 대한환경공학회 2019 대한환경공학회지 Vol.41 No.12

목적 : 본 연구에서는 G정수장의 2-MIB 처리 및 잔류 O₃ 제거를 위하여 Peroxone-Quenching 공정의 자동 제어 시스템을 개발하고 적정 약품을 선정하였다. 방법 : O₃ 공정을 통한 소독 효과 분석을 위하여 환경부에서 개발한 “소독능 계산 프로그램”으로 소독 공정(O₃, 잔류염소)별 Giardia 불활성화비를 계산하였다. Peroxone 공정 운영 최적화를 위해 운영 조건(O₃ 주입률, H₂O₂/O₃)에 따른 2-MIB 제거율을 분석하여 적정 약품 주입률 산정식을 도출하였다. Quenching 공정 최적화를 위한 적정 약품주입률 산정식은 용존 O₃ 농도와 대기 O₃ 농도의 상관관계, 적용 약품(H₂O₂, Na₂S₂O₃) 별 운영 조건(주입률, 수온 등)에 따른 용존 O₃ 감소율 분석을 통하여 도출하였다. Quenching 약품별 O₃ 제거 효율과 경제성을 분석하여 최적 약품을 선정하였다. 결과 및 토의 : 향후 용수생산량 증가 시에도 O₃ 소독 적정 운영으로 동절기 Giardia 불활성화비 1.0 이상 확보가 가능할 것으로 예상된다. 2-MIB 유입 시 Peroxone 공정 운영을 통하여 70-100%의 제거가 가능하였다. 2-MIB 제거율을 통해 적정 O₃ 주입률 산정식을 도출할 수 있었으며, 최적 H₂O₂/O₃는 0.4로 확인되었다. 대기 O₃ 농도 감소를 위해서는 용존 O₃ 제거가 필요하다. 약품별 용존 O₃ 제거 영향인자는 H₂O₂는 주입률, 접촉시간, 수온이며, Na₂S₂O₃는 주입률, 잔류염소로 확인되었다. 해당 인자를 적용한 Quenching 공정 최적운영을 위한 약품 주입률 산정식을 도출하였다. 약품별 주입률 모의 결과, Na₂S₂O₃의 O₃ 제거 효율이 H₂O₂보다 높고, 수온에 영향을 받지 않기 때문에 연중 대부분의 기간에는 Na₂S₂O₃ 주입률이 H₂O₂보다 낮게(6-96%) 운영할 수 있을 것으로 예상된다. Quenching 약품 연간 구매비는 H₂O₂ 131백만원, Na₂S₂O₃ 87백만원으로 산정되었다. Quenching 효율과 경제성 고려 시, 상시 Na₂S₂O₃ 적용이 타당할 것으로 판단된다. 결론 : G정수장 Peroxone-Quenching 공정 자동 제어 시스템이 구축되어 현재 운영 중이다. Peroxone 자동 제어 시스템 활용으로 2-MIB 유입 시에도 고품질 수돗물 생산이 가능할 것으로 예상된다. 또한 Quenching 공정 최적화로, 대기 O₃ 저감을 통한 작업장 안전성 확보와 경제적인 운영이 가능할 것으로 기대된다. Objectives : In this study, Peroxone-Quenching process auto control system was developed and appropriate chemical was selected for 2-MIB treatment and residual O₃ remove in G WTP. Methods : In order to analyze the disinfection effect by the O₃ process, the Giardia inactivation ratio by disinfection process (O₃, Cl) was calculated by “Disinfection efficiency calculation program” made by Ministry of Environment. To optimize the Peroxone process, the 2-MIB removal rate was analyzed according to the operating conditions (O₃ injection, H₂O₂/O₃) and the equation of chemical injection rate was derived. To optimize the Quenching process, the correlation between dissolved O₃ and atmospheric O₃, the reduction rate of dissolved O₃ concentration according to operation conditions (chemical injection rate, temperature, etc.) for each applied chemicals (H₂O₂, Na₂S₂O₃) were analyzed. And the equation of chemical injection rate was derived. To appropriate chemical for Quenching process was selected by analyzing O₃ removal efficiency and economic feasibility. Results and Discussion : When water production increases, it is expected that the optimal operation of the O₃ disinfection process will ensure the Giardia inactivation ratio over 1.0 in winter season. In the 2-MIB inflow, it was able to remove 70-100% of 2-MIB by Peroxone process operation. From the 2-MIB removal rate, an optimal O₃ injection rate equation could be derived and optimal H₂O₂/O₃ was confirmed to be 0.4. To reduce atmospheric O₃, dissolved O₃ remove is required. Factors affecting dissolved O₃ removal by chemicals were injection rate, contact time, water temperature for H₂O₂, and injection rate, residual Cl for Na₂S₂O₃. Using these factors, the equations of chemical injection rate for Quenching process were derived. As a result of the injection rate simulation for each chemicals, it is expected that the injection rate of Na₂S₂O₃ can be lower than H₂O₂ (6-96%). Because O₃ removal efficiency of Na₂S₂O₃ is higher than H₂O₂, and Na₂S₂O₃ is not affected by water temperature. The annual chemical purchase costs for Quenching process operation are estimated to be 131 million KRW for H₂O₂ and 87 million KRW for Na₂S₂O₃. Considering to Quenching efficiency and economic feasibility, the application of Na₂S₂O₃ was decided to be reasonable. Conclusions : The Peroxone-Quenching process auto control system was installed and is operated now. It is expected to produce high quality tap water even with 2-MIB inflow by Peroxone process auto control system. And by the optimization of Quenching process, atmospheric O₃ reduction for ensuring work place safety and economic operation would be expected.

후오존-고도산화+흡착과 자외선-고도산화+여과흡착 도입 정수장 실공정 운영결과 비교연구

장경아 ( Kyoung-a Jang ),박철종 ( Cheol-jong Park ),이영 ( Yeong Yi ),박종일 ( Jong-il Park ) 한국수처리학회 2018 한국수처리학회지 Vol.26 No.5

Recently a lot of Water Treatment Plants are being introduced the advanced treatment because they should produce and supply safe tap water for people in spite of polluted raw source water. By comparing and evaluating on-site data of Y and S regional WTP (water treatment plant) at operating at a high rate which have different advanced treatment processes, the purpose of this study is to draw key process variables and operating characteristics in terms of 3 categories including water quality improvement, operating convenience and cost analysis. Odor material 2-MIB (2-methylisoborneol) removal rates were over 70% of designed efficiency in both post O₃-AOP(advanced oxidation process) and UV-AOP process and the water quality improvement effect of advanced treatment process was verified in this study. Meanwhile, two types of oxidation process showed different difficulty levels at each process management categories such as chemical supply and facility maintenance. Lastly, by analysis of production cost, it was found that electric power and chemical production costs of UV-AOP+F/A process were relatively higher than that of post O3-AOP+GAC and the injection rate of 34% H₂O₂ is a key variable in both processes due to the high unite price of H₂O₂. Also in the post O₃ process, the injection rate of H₂O₂ for quenching residual dissolved O₃ increases the production cost. This study would be the important reference for the decision of the proper advanced treatment process and optimizing process operations.